The functional role of the intralaminar and midline thalamic nuclei has been considered non-specific because, taken together, the axons from these nuclei distribute throughout the cerebral cortex. But, since the corticipetal projections of these nuclei have not been examined individually as yet, it is premature to conclude that they are functionally non-specific. It may be that some of these nuclei are more closely associated with with particular cortical areas. Another major projection of the intralaminar nuclei is to the corpus striatum. Yet the organization of intralaminar ganglia is poorly understood. Therefore, a series of four projects has been designed to analyze the neural connections of the intralaminar and adjacent thalamic nuclei with the cerebral cortex and basal ganglia in the cat using state-of-the art neuroanatomical techniques. The first two projects are intended to determine the areal and laminar distribution of thalamocortical projections and the topographic organization of thalamostriatal projections from individual intralaminar and adjacent nuclei using anterograde autoradiographic axon-tracing and retrograde cell-labeling with horseradish peroxidase. The third project employs the recently developed fluorescence double retrograde cell-labeling techniques to determine the degree of collateralization of such thalamofugal fibers. The fourth project will be a comparison of the intrastriatal distributions of axons from the thalamus with those of other striatal afference-sources by the use of two different anterograde tracers in the same animal. The determination and comparison of these forebrain connections is essential to our understanding of the functional role of these important thalamic nuclei.